Bir dize olduğunda kötü uygulama olarak kabul denetlerken string.IsNullOrEmpty(string) string.IsNullOrWhiteSpace(string) bulunur .NET 4.0 ve üzeri?

Uygulamada söz konusudur

string testString = "";
Console.WriteLine(string.Format("IsNullOrEmpty : {0}", string.IsNullOrEmpty(testString)));
Console.WriteLine(string.Format("IsNullOrWhiteSpace : {0}", string.IsNullOrWhiteSpace(testString)));
Console.ReadKey();

Resutl :
IsNullOrEmpty : True
IsNullOrWhiteSpace : True

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string testString = " MDS   ";

IsNullOrEmpty : False
IsNullOrWhiteSpace : False

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string testString = "   ";

IsNullOrEmpty : False
IsNullOrWhiteSpace : True

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string testString = string.Empty;

IsNullOrEmpty : True
IsNullOrWhiteSpace : True

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string testString = null;

IsNullOrEmpty : True
IsNullOrWhiteSpace : True